feat(browser): error filters and linked error causes - #1146

Confidence 4/5 · likely safe to merge
F2's fix is real and the new filter path is unit- and browser-tested; only the frame-URL regex's less common formats are untested.
_{quality 100/100 · no findings · tests covered · risk medium}

Adds errors capture filters (ignore/denyUrls/allowUrls/beforeCapture plus default extension and ResizeObserver drops) evaluated before the exception span is created, and appends cause/AggregateError chains to exception.stacktrace. The global-regex fix at this head is correct; safe to merge.

• shouldCapture drops ignored, extension and ResizeObserver errors before recordException starts a span
• configureErrorFilters wires config.errors through init and the runtime shutdown
• exceptionOf appends Caused by: blocks from cause and AggregateError chains to exception.stacktrace
• window.onerror passes event.filename as the top frame when no Error was thrown

Fixed since the last review

• F2 · A /g regex in ignore/denyUrls/allowUrls matches only every other error

_{c095d88 · Updated on every push. Reply "won't fix" to dismiss a finding, or mention @maple to ask about one.}